Microwave ovens for preparing food are well known in prior art. Typically, uniform energy distribution within microwave ovens is desired because the food to be prepared should be heated uniformly. In addition a maximized power transfer to the food to be prepared should be achieved thereby keeping the microwave generator of the microwave oven working in the allowed impedance region.
Microwave ovens may comprise a turntable, on which the food to be prepared is located. By rotating the turntable, an evenly distributed heating of the food is obtained. Another type of microwave ovens comprises mode stirrers to achieve uniform heating. Said microwave ovens allow a variation of the working point of the microwave generator avoiding a critical operation in case of a mismatched load or even no load.
Impedance matching between the microwave generator and the oven cavity is obtained by a proper dimensioning and shaping of the interface between the oven cavity and the waveguide connecting the microwave generator with the oven cavity.
A drawback of the known microwave ovens is that rotating elements driven by a motor are necessary in order to obtain uniform heating, respectively, avoid critical operation in case of a mismatched load.